1. Field of the Invention
The present invention relates, in general, to vacuum generating devices and, more particularly, to a vacuum generating device designed to generate negative pressure in an absorption means, such as an absorption pad, of a vacuum system, such as a vacuum feeding system used on a production line, and release the negative pressure from the absorption means.
2. Description of the Prior Art
As well known to those skilled in the art, ejectors have been typically used for generating negative pressure in an absorption means in a vacuum system. Such an ejector may be separately installed in a vacuum system, to be used independently. Alternatively, such an ejector may be designed such that it constitutes a vacuum generating device in cooperation with some elements, such as a block body, a valve mechanism, etc., of the vacuum system.
Japanese Patent Laid-open Publication No. Heisei. 11-114862 discloses a typical example of conventional vacuum generating devices for such vacuum systems. The above conventional vacuum generating device comprises a single block body having a compressed air path, an ejector used for generating negative pressure in response to an action of the compressed air, and a control valve mechanism used for opening or closing the compressed air path of the block body. The ejector is provided at a side surface of the block body, while the control valve mechanism is provided in an upper portion of the block body. The vacuum generating device generates negative pressure in an absorption means of a vacuum system, and quickly releases negative pressure from the absorption means, as desired. Therefore, the vacuum generating device may be preferably used in a variety of vacuum systems, such as a vacuum feeding system used in an automated production line to feed workpieces to target places. However, the vacuum generating device is problematic in that the ejector is exposed outside the side surface of the block body, thus undesirably increasing the size of the device and being undesirably and easily removed from the block body by external shock.
In an effort to improve the structure and operational function of conventional vacuum generating devices, such as the above-mentioned Japanese device, U.S. Pat. No. 6,416,295 discloses another vacuum generating device, comprising a main body including four functional blocks arranged longitudinally and continuously, an ejector installed in the main body, and a control valve mechanism provided in an upper portion of the main body. The object of the above U.S. patent is to accomplish the recent trend of compactness and smallness of such vacuum generating devices by reducing the width of the device. However, the vacuum generating device disclosed in the above U.S. patent is problematic in that an undesired increase in the length of the device has resulted even though the device has a reduced width, so that compactness or smallness of the device has not been achieved. Another problem experienced in the vacuum generating device of the above U.S. patent resides in that the number of parts of the device has increased, resulting in an undesired increase in the production cost of the device.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a vacuum generating device, which accomplishes the recent trend of compactness and smallness of such devices, which effectively protects its ejector unit from damage, and does not have an increased production cost in comparison with conventional vacuum generating devices.
In order to accomplish the above objects, the present invention provides a vacuum generating device, comprising a block body having an air inlet port, a vacuum port and an air outlet port, an ejector unit functioning to generate negative pressure in response to an action of compressed air flowing into the ejector unit via the air inlet port, and a control valve mechanism functioning to open or close air supply paths branching from a main flow path to an air inlet chamber of the ejector unit and the vacuum port, the main flow path communicating with the air inlet port.
The present invention is characterized in that the block body has a recess, formed by depressing the surface of the block body to a predetermined depth, the ejector unit is formed in the recess by depressing predetermined portions of the recess, and a cover is set in the recess of the block body to seal the ejector unit from the outside. Preferably, the cover is designed such that its thickness is not greater than the depth of the recess of the block body.
In the present invention, the ejector unit is integrally formed in the block body such that the ejector unit is not exposed to the outside of the block body. Therefore, the vacuum generating device accomplishes the recent trend of compactness and smallness of such devices, and effectively protects its ejector unit from damage.